1. Field of Invention
The present invention relates to a unit for mounting an electro-optical device, such as a liquid crystal panel, to a prism, such as a dichroic prism or a polarization beam splitter, and to a projector using the same.
2. Description of Related Art
An example of a conventional projector relating to the present invention in which an electro-optical device, such as a liquid crystal panel, is mounted to a prism is disclosed, for example, in Japanese Unexamined Patent Publication No. 10-10994. Thus, the art disclosed in Japanese Unexamined Patent Publication No. 10-10994 will be briefly described with reference to an exploded view of FIG. 9.
A liquid-crystal-panel unit 70R is mounted to a light-incident surface 72R of a prism composition 72 of a projector. The panel unit 70R is composed of an innermost fixed frame body 76 bonded and fixed to the light-incident surface 72R of the prism composition 72, an outermost panel frame body 73 for accommodating and holding a liquid crystal panel 80R, and an intermediate frame body 77 disposed between the fixed frame body 76 and the panel frame body 73. The panel frame body 73 has a first frame body 74 and a second frame body 75, and further, holds the liquid crystal panel 80R by sandwiching between these frame bodies 74 and 75.
Engaging projections 77b projected outward from four corners of the intermediate frame body 77 are fitted and bonded into engaging holes 74b formed in four corners of the panel frame body 73 (the first frame body 74 thereof), and a spacer 78 having a substantially triangular prism shape is interposed between the intermediate frame body 77 and the panel frame body 73 so as to bond and fix the intermediate frame body 77 and the panel frame body 73.
Process steps for obtaining the above construction will be described hereinbelow with reference to a flowchart shown in FIG. 10.
That is, the fixed frame body 76 is first located on the light-incident surface 72R of the prism composition 72, and is bonded and fixed by an adhesive agent (S1). Then, the intermediate frame body 77 is located outside the bonded and fixed fixed frame 76, and is fixed by inserting four screws 79 into tapped holes 77a and 76a (S2).
Thereafter, an adhesive agent is charged into the engaging holes 74b that are formed in the first frame body 74 of the panel frame body 73 in which the liquid crystal panel 80R is accommodated and held, and the panel frame body 73 is attached to the intermediate frame body 77 by fitting the engaging projections 77b of the intermediate frame body 77 into the engaging holes 74b (S3).
Next, the liquid crystal panel 80R is turned on in this state (S4), and focus adjustment and alignment adjustment of the liquid crystal panel 80R are performed (S5 and S6). These steps S4 to S6 are performed to adjust the position of the liquid crystal panel 80R on the optical axis and the position of inclination relative to the position of the liquid crystal panel 80R.
Next, the adhesive agent charged in the engaging holes 74b is hardened to temporarily fix the intermediate frame body 77 and the panel frame body 73 (S7). Thereafter, a shift amount of the position of pixels of the liquid crystal panel 80R is checked (S8). Consequently, when the shift amount is beyond an allowable range (bad), the panel frame body 73 is removed (S13), and the procedure returns to the aforementioned step S3.
On the other hand, when the shift amount is within the allowable range (good), the adhesive agent is applied to the spacer 78 (S9), and the spacer 78 is mounted to a predetermined guide section formed between the temporarily fixed intermediate frame body 77 and the panel frame body 73 (S10). Then, by hardening the adhesive agent among the spacer 78, the panel frame body 73, and the intermediate frame body 77, the panel frame body 73 is actually fixed to the prism composition 72 (S11).
In the case of the above conventional device, however, the fixed frame body fixed to the prism projects over the outer periphery of the prism in order to secure a fixing screw hole, whereby a reduction in size of the device is hindered. In addition, since the structure requires the fixed frame body and the intermediate frame body, a further reduction in size of the prism unit is hindered.
Furthermore, many fixing devices and steps are required for fixing the liquid crystal-panel-unit to the prism, such as screws for fixing the fixed frame body and the intermediate frame body, a projection of the intermediate frame body and a hole of the panel frame body for temporarily fixing the panel frame body and the intermediate frame body, and a spacer and an adhesive agent for actually fixing the panel frame body and the intermediate frame body. Therefore, there is room for improvement from the viewpoints of operation efficiency and positioning accuracy.
Thus, the present invention proposes a projector capable of fixing an electro-optical device and a prism only by several fixing pins and an adhesive agent instead of a conventional fixed frame plate and a spacer to thereby achieve a reduction in size of the projector, simplification and an improvement in the efficiency of the fixing operation of the light synthesizer and the electro-optical device, and an increase in positioning accuracy.
In order to achieve the above object, the present invention employs a projector having an electro-optical device for modulating light, a prism to which the electro-optical device is mounted, and a projection lens for projecting modulated light. The projector may further include an electro-optical device frame body for holding the electro-optical device and having a plurality of holes provided in the periphery thereof, and fixing pins each having a flat part on one end surface thereof and inserted into the holes. The light-incident surface of the prism and the flat part of each of the fixing pins are fixed by an adhesive agent, and the insides of the holes of the electro-optical device frame body and an outer peripheral surface of each of the fixing pins are also fixed by an adhesive agent.
In addition, an electro-optical device-mounting unit for mounting an electro-optical device for modulating light to a prism, may include an electro-optical device frame body for holding the electro-optical device and having a plurality of holes provided in the periphery thereof. Fixing pins each having a flat part on one end surface thereof are inserted into the holes. A light-incident surface of the prism and the flat part of each of the fixing pins may be fixed by an adhesive agent, and the insides of the holes of the electro-optical device frame body and an outer peripheral surface of each of the fixing pins may be fixed by an adhesive agent.
According to these structures, the fixed frame body that has protruded from the periphery of the conventional prism is not required, so that a reduction in size of the device is achieved and moreover, it is possible to narrow a clearance between the prism and the electro-optical device frame body to a suitable range (within 3 mm, preferably 1 mm to 2 mm). Furthermore, since the number of assembling components is reduced and the fixing pins are placed in the holes, the positioning operation of the electro-optical device frame body is facilitated, and efficiency of fixing operation of the electro-optical device is improved. In addition, it is found from experiments that the fixing pins can be easily removed from the prism.
In addition, the contour of the electro-optical device frame body may be located at or inside of the outer periphery of the light-incident surface of the prism. According to this, the electro-optical device can be fixed at the inside of the outer periphery of the prism, and a reduction in size of the device can be achieved according to the size of the prism.
Also, the electro-optical device frame body may have substantially a rectangular shape, and the holes are provided in four corners of the electro-optical device frame body. According to this, the electro-optical device can be fixed to the prism by uniform force, positioning can be performed with higher accuracy, and the electro-optical device can be uniformly fixed to the periphery of the prism, so that impact resistance is improved.
Also, each of the fixing pins may have a deformed part at an end on the side different from the side on which the flat part is provided, and the deformed part protrudes from the surface of the electro-optical device frame body. According to this, the fixing pins can be easily inserted into the holes of the electro-optical device frame body by utilizing the deformed part for chucking, and positioning thereof can be easily performed.
In addition, each of the fixing pins may have a barrel shape in which central part is expanded. According to this, the electro-optical device frame body can be moved freely using the center part of the fixing pin as a fulcrum according to distortion of field of the projection lens, and the positioning operation of the electro-optical device is further facilitated.
In addition, each of the fixing pins may have a shape in which the central part is made thinner than both ends. According to this, elasticity of the fixing pin is improved at the central part, so that a stress applied to a bonded portion of the electro-optical device and the prism due to the difference in thermal expansion coefficient is reduced at this part, and a shift of pixels can be reduced.
Furthermore, the periphery of the flat part of each of the fixing pins may have chamfered, or a groove is provided in the outer peripheral surface on the side of the flat part of each of the fixing pins. According to this, it is possible to prevent the adhesive agent from flowing downward from the fixing pin.